/*
 * EAP peer method: EAP-GTC (RFC 3748)
 * Copyright (c) 2004-2006, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "eap_i.h"


struct eap_gtc_data {
        int prefix;
};


static void * eap_gtc_init(struct eap_sm *sm)
{
        struct eap_gtc_data *data;
        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;

        if (sm->m && sm->m->vendor == EAP_VENDOR_IETF &&
            sm->m->method == EAP_TYPE_FAST) {
                wpa_printf(MSG_DEBUG, "EAP-GTC: EAP-FAST tunnel - use prefix "
                           "with challenge/response");
                data->prefix = 1;
        }
        return data;
}


static void eap_gtc_deinit(struct eap_sm *sm, void *priv)
{
        struct eap_gtc_data *data = priv;
        os_free(data);
}


static struct wpabuf * eap_gtc_process(struct eap_sm *sm, void *priv,
                                       struct eap_method_ret *ret,
                                       const struct wpabuf *reqData)
{
        struct eap_gtc_data *data = priv;
        struct wpabuf *resp;
        const u8 *pos, *password, *identity;
        size_t password_len, identity_len, len, plen;
        int otp;
        u8 id;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_GTC, reqData, &len);
        if (pos == NULL) {
                ret->ignore = TRUE;
                return NULL;
        }
        id = eap_get_id(reqData);

        wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-GTC: Request message", pos, len);
        if (data->prefix &&
            (len < 10 || os_memcmp(pos, "CHALLENGE=", 10) != 0)) {
                wpa_printf(MSG_DEBUG, "EAP-GTC: Challenge did not start with "
                           "expected prefix");
                wpa_printf(MSG_DEBUG, "Unrecoverable error - Restarting\n");

                /* Send an empty response in order to allow tunneled
                 * acknowledgement of the failure. This will also cover the
                 * error case which seems to use EAP-MSCHAPv2 like error
                 * reporting with EAP-GTC inside EAP-FAST tunnel. */
                resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_GTC,
                                     0, EAP_CODE_RESPONSE, id);
                return resp;
        }

        password = eap_get_config_otp(sm, &password_len);
        if (password)
                otp = 1;
        else {
                password = eap_get_config_password(sm, &password_len);
                otp = 0;
        }

        if (password == NULL) {
                wpa_printf(MSG_INFO, "EAP-GTC: Password not configured");
                eap_sm_request_otp(sm, (const char *) pos, len);
                ret->ignore = TRUE;
                return NULL;
        }

        ret->ignore = FALSE;

        ret->methodState = data->prefix ? METHOD_MAY_CONT : METHOD_DONE;
        ret->decision = DECISION_COND_SUCC;
        ret->allowNotifications = FALSE;

        plen = password_len;
        identity = eap_get_config_identity(sm, &identity_len);
        if (identity == NULL)
                return NULL;
        if (data->prefix)
                plen += 9 + identity_len + 1;
        resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_GTC, plen,
                             EAP_CODE_RESPONSE, id);
        if (resp == NULL)
                return NULL;
        if (data->prefix) {
                wpabuf_put_data(resp, "RESPONSE=", 9);
                wpabuf_put_data(resp, identity, identity_len);
                wpabuf_put_u8(resp, '\0');
        }
        wpabuf_put_data(resp, password, password_len);
        wpa_hexdump_ascii_key(MSG_MSGDUMP, "EAP-GTC: Response",
                              wpabuf_head_u8(resp) + sizeof(struct eap_hdr) +
                              1, plen);

        if (otp) {
                wpa_printf(MSG_DEBUG, "EAP-GTC: Forgetting used password");
                eap_clear_config_otp(sm);
        }

        return resp;
}


int eap_peer_gtc_register(void)
{
        struct eap_method *eap;
        int ret;

        eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
                                    EAP_VENDOR_IETF, EAP_TYPE_GTC, "GTC");
        if (eap == NULL)
                return -1;

        eap->init = eap_gtc_init;
        eap->deinit = eap_gtc_deinit;
        eap->process = eap_gtc_process;

        ret = eap_peer_method_register(eap);
        if (ret)
                eap_peer_method_free(eap);
        return ret;
}
